Heat exchange structure



u 13, 1946- c. J. VlLLlER v 05,

HEAT EXCHANGE STRUCTURE Filed Feb. 27, 1943 s Sheets-Sheet 1 g--1 1946-I 6. J. VILLIER 2,405,722

HEAT EXCHANGE STRUCTURE Filed Feb. 27, 1943 5 Sheets-Sheet 2 13, 1945 c.J. VILL IER 7 2,405,722

. HEAT EXCHANGE STRUCTURE Filed Feb. 27, 1945 3 Sheets-Sheet 3 4 2.61% vA40 WWW Patented Aug. 13, 1946 UNITED STATES PATENT OFFICE HEAT EXGHANGE STRUCTURE Charles J. Villier, Louisville, Ky.

Application February 27, 1943, Serial No. 477,382

7 Claims. (Cl. 25'713'7) This invention relates to heat-exchange devicesof the type wherein heat is transferred in either direction between afluid passing through an enclosing, heat-transferring structure and asecond fluid contacting the exterior of the structure.

A primary object of the invention is to provide a tubular heat-exchangeelement having a crosssectional configuration that lends itself toformation by readily performed manufacturing methods, that is highlyspecialized to give heat-transfer of extremely high efiiciency; which haa form insuring transfer of uniform quantities of heat to or from theentire external surface area of the element; which is adapted to use ina large number of differently arranged assemblies; which gives anoptimum flow of fluid externally of the tubular heat-transfer element;and which gives an extended length of fluid flow interiorly of a coolingunit or system made of a plurality of the heat-transfer elements.

Another object of the invention is to provide novel assemblies of theelements herein disclosed, arranged to take full advantage of the highheattransfer capacity of such elements.

In the accompanying drawings:

Fig. I is a perspective fragmentary view showing the structuralarrangement of a heat-transfer element in accordance with my invention.

Fig. II is a similar view showing a plurality of elements as shown inFig. I in a stacked arrangement.

Fig. III is a perspective view of a heat-transfer element of modifiedform.

Fig. IV is a perspective view of a heat-transfer 7 element similar inform to the element shown in Fig. I, but made sectionally and equippedwith a liner tube.

Fig. V is a view showing a heat-transfer element having the modifiedform of Fig. III, made sectionally and equipped with a liner tubesimilarly to the structure shown in Fig. IV.

Fig. VI is a longitudinal sectional view through a plurality ofheat-transfer elements in accordance with Fig. I, showinginterconnection between elements to provide a continuous duct for fluidstherethrough.

Fig. VII is a schematic plan view of a length of heat-transfer elementin accordance with my invention, illustrating one mode of manufacturingthe elements to provide a continuous duct for fluids as shown in Fig.VI.

Fig. VIII is a schematic plan view illustrating a modified mode ofmanufacturing the heat- 2 transfer elements to provide a continuous ductfor fluids.

Fig. IX is a vertical sectional view through a plurality ofheat-transfer elements formed as in Fig. IV assembled to provide aheat-transfer unit assembly.

Fig. X is a fragmentary similar view of an analogous assembly, showingheat-transfer units in accordance with the showing of Fig. I.

Fig. XI is an elevational view, showing a heattransfer unit assembly asin Figs. IX and X, with the casing of the unit assembly partially brokenaway to show the general organization of the assembly.

Fig. XII is a perspective view of a further modifled form ofheat-transfer element.

Heat-transfer structure in accordance with my invention, as is usual inapparatus of that class, is purposed to effect heat-transfer between twofluids, which may be water or other liquid, air or other gas, steam, orother like or unlike matter in fluid state. The tubular elementdisclosed in Fig. I is of cross-sectional configuration that willproduce a uniform heat-transfer to or from a stream of fluid flowingthrough it and all parts of its external surface. Consequently,heat-absorption by the elements from a surrounding hotter fluid, ordissipation of heat to a cooler surrounding fluid, and transfer of suchheat through the body of the element will be at a uniform rate in alldirections from the bore of the elements to give heat-transfer ofexceptionally high efliciency.

To accomplish this uniformity of heat-transfer, the tubular body of suchan element is provided with longitudinal outwardly tapering fins orflanges I, designed not only to provide a relatively large externalsurface area as compared to the area of the internal surface 2surrounding the bore 3, but tapered in such a ratio of flange thicknessto distance from the surface 2 as to provide throughout each flange suchmass of heattransferring material as to maintain the entire externalsurface of the element at a uniform temperature. Heat-absorption orradiation of the entire surface of the element is thereby made uniform,making possible a full utilization of the heat-transmitting capacity ofthe material of which the element is made. The flanges I are separatedby channels 4.

Since the tubular elements are adapted for stacking in directlycontacting relation, the flanges l of such an element are not arrangedin uniform radiating arrangement around thebore of the element, but arearranged in two series projecting outwardly upon opposite sides of theelement. In order that face-to-face contact may be established in themanner shown in Fig, II, the elements are provided with opposit matchingunflanged surfaces extended between the outer surfaces of the bases ofthe marginal flanges. These surfaces 5 are provided with longitudinalgrooves G which provide passages for the external fluid when thesurfaces 5 of two elements are brought into contacting relation,extended inwardly from the channels 4 between the flanges. This providesfor heat transrnission to or from the portions of the surface 2 lyingbetween the areas correlated with the flanges. The grooves i5 and thechannels A. extend inwardly toward the bore 3 such distances as toprovide between their bases and the bore what is in effect a roundtubular body wall surrounding the bore, which wall is designated in thedrawings by reference numeral l. The arrangement of the flanges i,channels t, and grooves 6 is such as to maintain this wall structure '5at an approximately uniform temperature throughout its extent around thebore.

Elements having the configuration shown in the various forms of Figs. Ito V may be made by extrusion or casting, the former method beingpreferred in that it permits production of extended lengths which lendthemselves to formation of certain types of heat-exchange assemblies.The elements may be made of any material having suitable high capacityfor heattransfer and that can be formed in the required shape. Thecurrently available extrudable metals of high heat-transfer capacity andhigh ductility, such as aluminum and copper, are at present regarded aspreferred materials. The elements, as extruded, are of uniformcrosssectional configuration throughout their lengths.

Figs. I to V disclose various forms that elements having theconfiguration described may take. These various modifications are usefulin diiierent sorts of heat-exchange devices, and their selection dependsupon the arrangement of the particular device and the type of servicefor which it is intended.

Whereas the heat-transfer element shown in Fig. I comprises a one-piecetubular section, in Fig. III the element corresponds approximately toone-half the tubular form of Fig. I. In it there is but one group ofheat-conducting flanges l, which lie opposite a third unflanged face 8.The face 8 is flat, or is otherwise forms to match a surface againstwhich the heat-transfer elements are mounted. This form of element alsohas in its opposed matching faces 9 grooves ill corresponding to thegrooves 6 of the form of heat-transfer element shown in Fig. I.

For making up heat-transfer elements of composite structure, the tubularelements may be extruded, or otherwise formed, in two sections.Desirably, like complete sections, these semitubular elements areextruded from a suitable extrudable metal of high heat-transferproperties, such as aluminum. As shown in Fig. IV, two such semi-tubularelements, designated ii and 12, may be assembled in opposed relation toform a complete tubular element of the same form as the one-pieceelement of Fig. I, the element being suitably secured together as bybrazing, soldering, or welding, and in assembly enclose between themsimple light-walled tubing l3. Such an assembly is particularly usefulwhen the fluid to be passed through the element is reactive with thematerial of which the element is formed, since the tube It may be madeof a material that is inert to the fluid. A structure havingsubstantially the same ultimate advantages may be made by internallycoating the bore of the one-piece element in Fig. I with a suitablecoating material, or by lining it in any other suitable way, for exampleby expanding a seamless ductile tube within the bore.

Fig. V shows a semi-tubular section M assembled with a second, modifiedsemi-tubular section E5. The section t5, instead of being provided witha series or group of flanges, has an unfianged lateral surface it whichis arranged substantially opposite th group of flanges l in assembly. Asshown in Fig. V, the heat-transfer element is formed of the partialsections !4 and i5 connected around and embracing the lightwalled tubeis, to give a composite structure in which the general organizationshown in Fig. IV is applied to an element having the form shown in Fig.III.

Tubular elements, such as those shown, may be used with great advantagein heat-exchanging devices generally. The cross-sectional form of theelements permits their formation in a variety of ways into compactheat-exchange devices having peculiarly stable and strong construction,which permits the employment of highly ductile material in the elementswithout production of fragile structures. The configuration of suchdevices is also such as to present minimized resistance to fluidsflowing through them, and longitudinally along their exterior surface.

Referring to Figs. II and VI, it will be seen that the device comprisesa vertical stack of tubular heat-exchange elements, or reaches ofheat-exchange elements, designated in assembly by reference numeral i8,which are arranged in directly contacting superposed relation. Theinternal bores of the tubular elements or reaches [8 are connected byU-shaped tubular connections ll. Such connection may be made in severalways.

In the form shown in Fig. VII a continuous tube is bent to serpentineform, having parallel straight reaches l8 that are connected at theirends by the U-shaped bends H. The bore 28 through the stack is thuscontinuous, and in the straight, mutually contacting reaches l8 has theheat-transferring jacketing provided by the flanges I. In preparationfor bending, the tubular structure is stripped of its flanges in aplurality of longitudinally spaced regions 2|, and is brought to asimple round section as by grinding, turning, or some similar operation.These stripped regions 2| are utilized to provide the bends i7.

As shown in Fig. VIII, a long assembly structure is made by mounting aseries of flanged heattransfer elements in spaced relation on a tube l3,the regions 13a of the tube lying between the flanged elements providingsimple tubular structure for making the bends. This assembly may be madein at least two diflerent ways. In accordance with one method ofmanufacture, flanged heat-transfer elements as shown in Fig. I areskipped along the tube into properly spaced positions, and the tube isthen expanded into secure engagement with them and is bent.Alternatively, heat-transfer elements longitudinally divided into twosectional parts are placed in matched position to surround tube l3 atspaced intervals, and are secured in position as by welding, or brazing,to leave between them the free tube regions l3a for the connecting bendsIT. The showing of Fig. VIII is thus consistent with the application totube l3 of heat-transfer elements in accordance with the showing of Fig.I and Fig. IV. It is to be understood, however, that heat-transferelements formed as in Fig. III or Fig. V similarly may be applied tosurround the inner tube l3.

With any of these forms, the structure is so bent as to provide acontinuous Serpentine tube, in

which as shown in Fig. VI the straight reaches IS A are of finned, orflanged, structure and the bends I! are of simple tubular structure. Asshown in Fig. VI and other figures of the drawings, unflanged faces ofthe flanged heat-transfer lengths are brought into stacked relation toform a compaot assembly, the continuous serpentine bore, or duct, ofwhich is of relatively great length. The advantage derived fromutilizing extruded lengths of heat-transfer structure trimmed atintervals for bending, or in mounting a plurality of sections of suchstructure on a liner of thin wall tubing, are obvious.

It is to be understood that instead of bending the structure of theheat-transfer element proper,

or bending a tube upon which a plurality of the heat-transferringelements are mounted, interconnection between straight lengths of theheattransfer elements may be made in other though currently lessdesirable ways.

An important advantage rising from my invention is that in an assemblyof the heat-transfer elements to form a heat-transfer unit theheattransfer elements so match as to provide unobstructed flow of fluidaround and along the heattransfer elements. This will be readilyapparent from a consideration of Figs. IX, X, and XI. Fig. IX of thedrawings shows a plurality of heattransfer elements made up as in Fig.IV of the drawings, mounted in stacked and matched arrangement within acasing 22, as a heat-transfer unit. Fig. XI of the drawings shows-thestructural arrangement of such unit as a whole. In accordance with theshowing of Fig. XI a fan 23 draws air through inlet 24 of the casingpast the heat-transfer elements to outlet opening 25.

Assuming then that some fluid, such as water, is passed through theserpentine duct provided by the several straight reaches #8 and bends I?of the heat-transfer structure, it is subjected in passage to theheating or cooling effect of a fluid, such as air, drawn through thecasing. The air flow (referring to Figs. IX and XI) is through thelongitudinal passages 25 between flanges l of the heat-transfer elementsand through their extensions 21 formed by the grooves ID in the matchingfaces of the heat-transfer elements. This flow is uninterruptedlongitudinally of the reaches of the heat-transfer elements, because ofthe longitudinal arrangement of the heat-transfer flanges l which theycarry. This prevents the formation of eddies and regional vacuum effectswhich serve greatly to impair heat-transfer in conventional radiatorstructures.

In a structure wherein a fluid is forced at right angles past a seriesof straight tubes, a turbulence is set up, tending to produce a vacuumcovering a rear segment of each tube through its entire length so thatheat is absorbed or dissipated only at the front and sides of the tube.In a heattransferring assembly utilizing the heat-transfer elements ofmy invention, there are no dead spots caused by vacuum, inasmuch as airflow through passages 26 and their extensions 21 is along the reaches ofthe heat-transfer elements,

and is in contact with a great surface area of metal forming thestructure of the heat-transfer elements in its passage. In an assemblysuch as is shown in Figs. IX and XI, the only vacuum effect present isin regions 28 immediately to the rear of the bends ll. Also consideringFigs. IX and XI of the drawings, it will be seen that the circuitousserpentine path which fluid in the duct of the structure is caused tofollow gives an extended travel, during all of which the fluid issubjected to heat-transfer under conditions of high heat-transferefliciency.

Fig. X or the drawings shows in fragmentary manner an assembly such asthat shown in Fig. IX, except that the form of heat-transfer element isas shown in Fig. I, rather than as shown in Fig. IV, the bore throughthe straight reaches of the heat-transfer element proper being formed byits own structure without a liner tube, and interconnection between theends of the elements being provided as in Fig. VII, or in some othersuitable manner.

In making up composite elements such as those responding to Figs. IV andV which include a liner tube of heat-transfer material, the compositionof the tube may be adapted to the fluid which the element is expected toreceive. Thus if a heattransfer unit is purposed to contain a fluidwhich exerts a destructive effect on the metal of which theheat-transferring elements, or jacket structure of the assembly iscomposed, the tube may be of an unlike metal inert to that fluid. Thisgives great flexibility in the selection of metals for the primarystructure of the elements, while insuring against rapid destruction ofthe elements under particular service conditions. Conversely thechemical properties of the outer elements, or jacket, of the assemblymay be made of metal resistant to a fluid which would attack the linertube of the assembly.

Fig. XII of the drawings shows a modified form of heat-transfer elementwhich is closely analogous to the heat-transfer element shown in Fig. I.In this heat-transfer element, designated generally by reference numeral29, the bore 3!] through the element is elongate instead of circular,and an increased number of heating flanges I are provided. The matchingfaces 3| and 31a of the heat-transfer element are provided withlongitudinal grooves 32 to form continuations of the passages betweenthe flanges I when the heattransfer elements are stacked in matchingassembly. This modified form of heat-transfer element is included toillustrate changes which may be made in the structural arrangement ofthe heat-transfer element while retaining the novel features of theheat-transfer element shown in preceding figures of the drawings.

It will readily be understood that an assembly such as is shown isexemplary only of many assembly arrangements in which heat-transferelements may be incorporated. It is, however, an inherent characteristicof my heat-transfer elements that they are peculiarly adapted toassembly in unit heat-transfer devices, a plurality of which may furtherbe associated. Thus for example in a heating or cooling installation, aplurality of heat-transfer units such as those shown in Figs. IX and XImay be utilized. An assembly of a plurality of serpentine units betweentwoheaders may also advantageously be made. Such assembly also presentsa very material practical advantage in that it enables selectivedismounting of any one serpentine unit by disconnecting it from theheaders. Thus a damaged unit can be replaced without dismantling theentire assembly, as is required in an assembly of straight tubesconnected to two spaced headers.

I claim as my invention:

1. A heat-exchange assembly comprising a continuous tube rebent intoserpentine form, with parallel straight reaches in superposed relation,the said straight reaches having opposite matching surfaces thatrespectively contact in faceto-face relation in the straight reaches andhaving longitudinally disposed laterally projectant heat-transferflanges, and longitudinally extended grooves in the structure of thesaid straight reaches adjacent the opposite matching surfaces thereofarranged in the assembly to provide channels for the flow of fluidsubstantially to equalize heat-transfer in the surfaces matching inface-to-face contact with'that in the flanged regions of the saidstraight reaches.

2. A heat-exchange assembly comprising a plurality of straight reachesof tubular heattransfer structure arranged in parallel and stackedrelation, adjacent ends of successively adjacent reaches of the assemblybeing interconnected to provide a continuous serpentine duct through theassembly, the said several reaches having opposed surfaces which matchin face-toface contact in the stacked assembly and each reach having atleast one other surface which is flanged, and longitudinally extendedgrooves in the structure of the said straight reaches adjacent theopposed matching surfaces thereof arranged in the assembly to providechannels for the flow f fluid substantially to equalize heattransfer inthe surfaces matching in face-to-face contact with that in the flangedregions of the said straight reaches.

3. A heat-exchange assembly comprising a continuous tube, opposedportions of said tube being substantially straight and parallel, suchstraight portions beingin superimposed contacting relationship,unflanged portions connecting said straight portions and flangesintermediate said unflanged portions, the flanges being coextensive withthe straight portions and being symmetrically disposed, each of suchcontacting portions being provided with a flat surface separated bygrooves so that a flat surface of one portion abuts a flat surface of asuperimposed portion and whereby the grooves in one portion mate withthe grooves in a superimposed portion to form fluid passageways, acasing surrounding said tube, said casing having openings adjacent saidunflanged connections, and a fan mounted in one opening whereby a fluidmay be caused to move longitudinally of the straight portions andflanges.

4. A heat-exchange assembly comprising a continuous tube, opposedportions of said tube being substantially straight and parallel, suchstraight portions being in superimposed contacting relationship,unflanged portions connecting said straight portions, and groups offlanges intermediate said unflanged portions, the flanges beingcoextensive With the straight portions and one group of flangesalongside a pair of straight portions being symmetrically arranged withanother group on the other side of said pair of straight portions eachof such contacting portions being provided with a flat surface separatedby grooves so that a flat surface of one portion abuts a flat surface ofa superimposed portion and whereby the grooves in one portion mate withthe grooves in a superimposed portion to form fluid passageways, acasing surrounding said tube, said casing having openings adjacent saidunflanged connections, and a fan mounted in one opening whereby a fluidmay be caused to move longitudinally of the straight portions andflanges.

5. A heat exchange duct structure comprising an elongate tubular bodyfor separating two fluids for exchange of heat between them; said bodyhaving two opposite unflanged surfaces complementary in contour, saidunflanged surfaces being joined by two other surfaces at least one ofwhich is provided with longitudinal flanges, each of said unflangedsurfaces being provided With longitudinally extending grooves, the baseof one of said flanges being disposed adjacent a groove in one of saidunflanged surfaces there being a straight flat surface disposed betweengrooves in each of said unflanged surfaces.

6. A duct as defined in claim 5 wherein one of such surfaces joining theunflanged surfaces is substantially flat.

Z. A duct as defined in claim 5 wherein both of such surfaces joiningthe unflanged surfaces are provided with flanges.

CHARLES J. VILLIER.

